Knowledge Management System Of Institute of process engineering,CAS
|Thesis Advisor||齐涛 ; 陈德胜|
|Place of Conferral||北京|
|Keyword||含钒钛渣 钒 浸出 碳化 沉钒 萃取|
钒钛磁铁矿是我国重大特色战略矿产资源，其主要含有铁、钒和钛等金属元素，我国75%-85%的钒来源于钒钛磁铁矿。传统的钒钛磁铁矿冶炼方法以高炉法为主，其钒、钛回收率低，钛资源无法利用，难以实现有价资源的高效利用。近年来提出的直接还原技术，尽管可提高钒、钛的回收率，但需要多步高温实现钒和铁的提取，流程长、能耗高。基于此，针对辽宁地区钒钛磁铁精矿其铁品位低和钒、钛品位高的原料特点，传统工艺难以处理，中国科学院过程工程研究所提出了“钠化提钒-还原提铁”耦合新工艺，通过一步高温实现铁的还原-熔分和钒的氧化钠化。本文针对还原工序得到的含钒钛渣，展开了钒的高效提取研究，重点研究了含钒钛渣浸出过程中主要工艺条件的影响，并进行钒的浸出动力学及浸出机理的研究；开发了强碱性含钒浸出液“碳化-萃取/反萃”实现碱回收及钒提取的工艺路线。论文的主要研究内容和成果如下： （1）系统研究了含钒钛渣浸出的工艺条件，并对钒的浸出过程宏观动力学及浸出机理进行了深入的研究。研究结果表明，在优化条件下，经过三级逆流浸出，可分别实现钒、钠、硅83.8%、72.8%、16.1%的浸出率。含钒钛渣中钒的浸出过程符合未反应收缩核模型，受内扩散控制，表观活化能为11.2kJ?mol-1。钒浸出率只有83.8%的原因是部分的钒被包裹在钙钛矿相中不能被浸出，同时少量钒在焙烧过程中未被氧化而无法被浸出。（2）对强碱性含钒浸出液进行了CaO沉钒和萃取提钒实验研究。研究结果表明，对强碱性含钒浸出液采用CaO沉钒和萃取提钒时，需要降低溶液pH至7～10，同时降低溶液中硅酸根、铝酸根的影响。为实现溶液中Na的回收，对强碱性体系含钒浸出液提出碳化-萃取/沉钒-钒产品的工艺路线。（3）系统研究了强碱性含钒溶液碳化过程的技术路线和工艺条件。研究结果表明，碳化过程随着pH不断降低，pH降低到10之前主要实现溶液中Al、Si的析出，pH从10降低到8过程中主要实现溶液中Na的析出。确定两步碳化过程实现Al/Si与Na的选择性分离与回收。 （4）对碳化液进行CaO沉钒和萃取提钒系统实验研究。研究结果表明，在优化条件下，分步沉钒可实现钒93.78%的沉淀率，沉淀物中V2O5的含量为7.84%；萃取提钒研究中，加入10g?L-1CaO除去部分HCO3-影响，在优化条件下，经四级逆流可实现钒90.2%的萃取率，并对萃取有机相通过NH4Cl-NH4OH反萃可一步得到钒沉淀。因此，对含钒钛渣提出“浸出-两步碳化-CaO除杂-萃取-反萃/沉钒”的工艺路线。
Vanadium-titanium magnetite is a major characteristic of strategic mineral resources in China, which mainly contains iron, vanadium, titanium and other metal elements. 75% to 85% of vanadium is extracted from vanadium-titanium magnetite in China.The traditional smelting method of vanadium-titanium magnetite is blast furnace, which recovery rate of vanadium and titanium is low, and it is unable to achieve efficient use of the valuable resources. In recent years, direct reduction technology was proposed, which can increase the recovery rate of vanadium and titanium, but it needs multisteps high-temperature roasting which leads to high energy consumption. Based on the research status, in consideration of the raw material characteristics of Liaoning ultra-lean low grade vanadium-titanium magnetite, a new coupling technology of Na-activation for vanadium-reduction for iron was proposed by Institute of process engineering, CAS, aiming at achiving the melting points of iron and sodium vanadate. This paper expands the efficient extraction and basic research of vanadium for the V-Ti slag obtained by the new technology. Focus on the effects of main conditions on the leaching process, and conducting the kinetics and mechanism research of the vanadium leaching process. At the same time the research obtained highly alkaline vanadium-containing leach solution carbon points-extraction/stripping process route achieving the recovery of vanadium. The main contents and results are as follows: (1) A systematic study for the leaching conditions of V-Ti slag, and conducted in-depth research for the kinetics and mechanism of vanadium leaching process. The results show that under optimum conditions, after three countercurrent leaching, 83.8%、72.8%、16.1% of vanadium、sodium and silicon can be leached out, respectively. The vanadium leaching process could be well described by the unreacted shrinking core model. The leaching of vanaidum were controlled by mass diffusion, and the apparent activation energies were 11.2kJ?mol-1.The 83.8% of vanadium leaching rate could be ascribed to two factors: one is that a fraction of the vanadium was trapped in the phase of calcium titanate, whereas the other is that the fraction of V3+ was not fully oxidized during the roasting process. (2) Vanadium precipitation of CaO and solvent extraction for the strong alkaline leaching solution has been systematically studied. The results show that it needs to reduce the pH to the optimum range and reduce the concentration of silicate, aluminate in the solution, when conducting vanadium precipitation or solvent extraction. To achieve the recoveryof Na in the solution, a carbonize-solvent extraction/CaO precipitaion vanadium products processing route was proposed for the strong alkaline leaching solution.(3) A systematic study of technical route and process conditions of carbonization process for the strongly alkaline solution. The results show that, the pH continue to be lower during the carbonization process, when the pH is higher than 10, it is mainly realizing the precipitation of Al and Si from the solution; while when the pH is lower than 10, it is mainly realizing the precipitation of Na from the solution.So the sub-step carbon impurity-sodium recovery process route was determined.(4) A systematic study of CaO precipitaion and solvent extraction of vanadium for the carbonized liquid. The results show that, under the optimal conditions, 93.78% of vanadium can be precipitated by fractional precipitation, and the content of V2O5 in the precipitate is 7.84%. In the solvent extraction study, adding 10g?L-1 CaO to remove the impact of HCO3-, 90.2% of vanadium can be extracted by four countercurrent extraction process, and vanadium precipitate can be obtained by by NH4Cl-NH4OH stripping. Therefore, A leaching-step carbonization-CaO impurity- extraction-stripping/vanadium precipitation process route was proposed for the V-Ti slag.
|朱媛媛. 含钒钛渣提钒中钒的迁移特性与工艺优化[D]. 北京. 中国科学院研究生院,2016.|
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